The inflammatory bowel diseases are complex genetic disorders. Whole genome scanning to identify chromosomal regions containing disease loci will be performed. Affected pedigree member pairs will be genotyped by polymerase chain reaction amplification of microsatellite markers using fluorescent labeled primers. M01RR000550678 This Phase I-II study is designed to evaluate oral tolerance and efficacy of a novel peripheral opioid antagonist, methylnaltrexone. This parmocokinetic based study will allow us to obtain first ever information of oral dose of methylnaltrexone in preventing the opioid-induced changes in gastrointestinal motility and transit.